Satellite Laser Ranging (SLR) is a technique that calculates the distance at the mm precision level by emitting a laser beam from the ground station to a specific geodetic satellite and measuring the round trip time of the laser beam reflected and then returned and utilizes the result values of the observation in geodetic survey and geodynamics research and the high precision determination of the orbit of an geodetic satellite. A satellite that is tracked or observed is generally located in an altitude range of 300 km to 23,000 km. In some cases, the satellite may be the COMPASS satellite at an altitude of 42,000 km or a lunar probe satellite, such as Apollo.
In order to select a satellite continuously traveling along an orbit in outer space and emit a laser beam to the satellite from the ground and receive the returned laser beam at an observatory on the ground, special precise technologies are required. In particular, among these technologies, a tracking mount that tracks the current position of a satellite so that laser beams are successively emitted to the satellite via an optical telescope and then received is very important.
Conventional telescopes are chiefly used to perform astronomical observations. Since the telescopes that are used to perform astronomical observations do not require high-speed tracking, equatorial mounting is chiefly employed. However, SLR needs to track the orbits of various satellites, and, in particular, a low-orbit satellite requires high-speed tracking, in which cases altitude-azimuth mounting is employed.
In the case of ARGO-M, which is a mobile SLR system currently under test operation, the diameter of a primary telescope should be 40 cm, and the track precision of a tracking mount should be within 5 arcsec. This means that a satellite can be tracked at a precision within 5 arcsec in spite of the process of transferring the command to track a satellite from an operation system, the uncertainty of the calculation that may occur in the tracking mount, and communication delay.
That is, there is a demand for a system that is capable of performing accurate orbit estimation and operating an optical telescope in accordance with an estimated value in order to enable the accurate position tracking of a satellite via the emission of a laser beam, which is the inherent mission of ARGO-M.